Paramagnetic iron, at the active site in hemoproteins, is bonded to four nitrogens in the planar heme group. Additional bonds to ligands out of the heme plane vary with the protein. The electron spin relaxation rate of iron has been measured as a function of temperature in only three low spin hemoproteins, but in each case an anomalous temperature dependence has been observed which suggests that the iron interacts only with ionic vibrations of the heme plane. Nevertheless there are large variations among the relaxation rates of various low spin hemoproteins and we are studying a series of them to determine the similarities and differences among hemoproteins with varying proximal and distal ligands. Specifically, we fit the Raman relaxation rate to a function of the form CTnJn-1 (theta D/T). Here C is the strength parameter, n is an integer, the value of which has been 7 for hemoproteins instead of 9 which characterizes non-heme ferric systems, Jn-1 is a transport integral, theta D is the Debye temperature of the protein, and T is the absolute temperature. Current studies on myoglobin azide yield n equals 7, theta D equals 73.7K, and C equals 2.55 10 to the minus 6th power s to the minus first power K to to the minus 7th power. These should be compared to 7, 75K, and 3.9 10 to minus 7th power s to the minus first power K to the minus 7th power for P-450 from Pseudomonas putida.